Back to EveryPatent.com
United States Patent |
5,167,615
|
East
,   et al.
|
*
December 1, 1992
|
Flow control device having selectable alternative fluid pathways
Abstract
A flow control device for use in a subcutaneously implanted physiological
shunt system includes a relatively rigid base and a resiliently flexible
encasement which defines a fluid flow path therethrough from an inlet to
an outlet. Two valves for controlling the flow of fluid through the device
are situated within the fluid flow path between the inlet and the outlet.
The fluid flow path includes a first fluid conduit which directs fluid
through both valves, and a second fluid conduit which bypasses the first
valve and directs fluid only through the second valve. The first valve is
constructed to provide a greater resistance to flow through the device
than the second valve, and when the second fluid conduit is unobstructed,
fluid will tend to flow through the second fluid conduit and bypass the
first valve. A pivotable plug is provided within the encasement for
selectively occluding a portion of the second fluid conduit. The position
of the plug is determined by a magnetically polarized, percutaneously
manipulable cam also provided within the encasement. The plug and the cam
are attached such that rotation of the cam in one direction causes the
plug to occlude the second fluid conduit, and rotation of the cam in
another direction opens the second fluid conduit to fluid flow. A siphon
control device is provided adjacent to the outlet to prevent fluid flow in
response to negative downstream hydrostatic pressure on the outlet of the
device.
Inventors:
|
East; Gary P. (Santa Barbara, CA);
Watson; David A. (Goleta, CA)
|
Assignee:
|
Pudenz-Schulte Medical Research Corporation (Goleta, CA)
|
[*] Notice: |
The portion of the term of this patent subsequent to October 13, 2009
has been disclaimed. |
Appl. No.:
|
694896 |
Filed:
|
May 2, 1991 |
Current U.S. Class: |
604/9; 137/854; 604/247 |
Intern'l Class: |
A61M 027/00 |
Field of Search: |
604/8-10,247,186
137/854
|
References Cited
U.S. Patent Documents
4552553 | Nov., 1985 | Schulte et al.
| |
4560375 | Dec., 1985 | Schulte et al. | 604/9.
|
4636194 | Jan., 1987 | Schulte et al.
| |
4741230 | May., 1988 | Dormandy, Jr. et al. | 604/8.
|
4761158 | Aug., 1988 | Schulte et al. | 604/9.
|
4781673 | Nov., 1988 | Watanabe | 604/9.
|
4781674 | Nov., 1988 | Ridmond et al. | 604/9.
|
4795437 | Jan., 1989 | Schulte et al. | 604/10.
|
4850955 | Jul., 1989 | Newkirk | 604/9.
|
4861331 | Aug., 1989 | East et al. | 604/9.
|
4867740 | Sep., 1989 | East | 604/9.
|
4867741 | Sep., 1989 | Potnay | 604/10.
|
4995864 | Feb., 1991 | Bartholemew et al. | 604/9.
|
Primary Examiner: Hafer; Robert A.
Assistant Examiner: Owens; Kerry
Attorney, Agent or Firm: Kelly, Bauersfeld & Lowry
Parent Case Text
RELATED APPLICATION
This is a continuation-in-part application of U.S. patent application Ser.
No. 07/524,136, filed May 15, 1990 , now U.S. Pat. No. 5,154,693, and
entitled FLOW CONTROL DEVICE HAVING SELECTABLE ALTERNATIVE FLUID PATHWAYS.
Claims
We claim:
1. A fluid flow control device, comprising:
a housing having an inlet and an outlet;
a first fluid flow pathway through the housing from the inlet to the
outlet, the first fluid flow pathway having first means including a first
valve for resisting fluid flow therethrough;
a second fluid flow pathway through the housing from the inlet to the
outlet, the second fluid flow pathway having second means including a
second valve for resisting fluid flow therethrough, wherein the first
fluid flow pathway directs fluid through the first and second valves, and
the second fluid flow pathway bypasses the first valve and directs fluid
through the second valve; and
means for selectively directing fluids through one of the first or the
second fluid flow pathways, the fluid directing means being actuable by
percutaneous manipulation of the device when subcutaneously implanted.
2. A fluid flow control device as set forth in claim 1, wherein the first
and second valves each comprise a base including a valve passageway
therethrough and a valve seat surrounding a portion of the valve
passageway, and a flow control member contacting the valve seat in a
manner normally occluding the valve passageway but selectively opening to
permit controlled unidirectional flow therethrough.
3. A fluid flow control device as set forth in claim 2, wherein each flow
control member includes a central support and a resilient membrane, the
central support being attached to the respective base and extending
therefrom to support the resilient membrane, the resilient membrane being
generally arch-shaped and having a portion thereof capable of engaging the
respective valve seat to occlude the respective valve passageway.
4. A fluid flow control device as set forth in claim 1, wherein the first
valve provides a greater resistance to flow than the second valve.
5. A fluid flow control device as set forth in claim 1, wherein the means
for selectively directing fluids through either the first or the second
fluid flow pathways includes means for occluding the second fluid flow
pathway.
6. A fluid flow control device as set forth in claim 5, wherein the means
for occluding the second fluid flow pathway includes a selectively
positionable plug movable between a first position wherein the second
fluid flow pathway is open to fluid flow therethrough, and a second
position wherein the second fluid flow pathway is closed to fluid flow
therethrough.
7. A fluid flow control device as set forth in claim 6, wherein the means
for occluding the second fluid flow pathway includes a magnetically
polarized, percutaneously manipulable cam rotatable between a first
position and a second position, the plug having an occluder at one end and
a cam rider at another end, wherein the cam rider interacts with the cam
such that rotation of the cam between its first and second positions
simultaneously moves the plug between its first and second positions.
8. A fluid flow control device as set forth in claim 1, including a pump
between the inlet and the outlet, wherein the pump provides means for
flushing fluid from the fluid flow control device by application of
percutaneous manual pressure to the device.
9. A fluid flow control device as set forth in claim 8, including means for
temporarily occluding a portion of the fluid flow pathways adjacent to the
inlet by application of percutaneous manual pressure to the housing such
that actuation of the pump flushes fluid distally through the device.
10. A fluid flow control device as set forth in claim 8, including means
for temporarily occluding a portion of the fluid flow pathways adjacent to
the outlet by application of percutaneous manual pressure to the housing
such that actuation of the pump flushes fluid proximally through the
device.
11. A fluid flow control device as set forth in claim 1, including siphon
control device means situated adjacent to the outlet and forming a portion
of the fluid flow pathways, for preventing fluid flow through the device
in the presence of negative hydrostatic pressure at the outlet.
12. A subcutaneously implantable shunt system, comprising:
a shunt inlet;
a shunt outlet;
first valve means for controlling fluid flow from the shunt inlet to the
shunt outlet;
second valve means for controlling fluid flow from the shunt inlet to the
shunt outlet;
first fluid conduit means for directing fluid through the first and second
valve means as the fluid passes through the shunt system;
second fluid conduit means for directing fluid through the second valve
means and bypassing the first valve means as the fluid passes through the
shunt system; and
means for selectively directing fluid either through the first or second
fluid conduit means, the fluid directing means including a selectively
positionable plug movable between a first position wherein the second
fluid conduit is open to fluid flow therethrough and a second position
wherein the second fluid conduit is closed to fluid flow therethrough, and
a magnetically polarized, percutaneously manipulable cam rotatable between
a first position and a second position, the plug having means for
occluding the second fluid conduit at one end and a cam rider at another
end, wherein the cam rider interacts with the cam such that rotation of
the cam between its first and second positions simultaneously moves the
plug between its first and second positions.
13. A shunt system as set forth in claim 12 including a pump situated
between the shunt inlet and the shunt outlet, wherein the pump provides
means for flushing fluid through the shunt system by application of manual
percutaneous pressure to the pump.
14. A shunt system as set forth in claim 12, including means for occluding
a portion of the shunt system adjacent to the inlet by application of
manual percutaneous pressure to the shunt system, and means for occluding
a portion of the shunt system adjacent to the outlet by application of
manual percutaneous pressure to the shunt system.
15. A shunt system as set forth in claim 12, including siphon control
device means situated between the second valve means and the outlet, for
preventing fluid flow through the device in the absence of negative
hydrostatic pressure at the outlet.
16. A shunt system as set forth in claim 12, wherein the first and second
valve means each include a base having a fluid passageway therethrough and
a valve seat surrounding a portion of the fluid passageway, and a flow
control member which contacts the valve seat in a manner normally
occluding the fluid passageway but selectively opening to permit
controlled unidirectional flow therethrough.
17. A shunt system as set forth in claim 16, wherein each flow control
member includes a central support and a resilient membrane, the central
support being attached to the respective base and extending therefrom to
support the resilient membrane, the resilient membrane being generally
arch-shaped and having a portion thereof capable of engaging the
respective valve seat to occlude the respective fluid passageway.
18. A shunt system as set forth in claim 13, wherein the fluid directing
means is situated within the pump, the first valve means is situated
between the shunt inlet and he pump, and the second valve means is
situated between the pump and the shunt outlet.
19. A flow control device having selectable alternative fluid pathways, for
use in a subcutaneously implanted physiological shunt system, the flow
control device comprising:
a housing having an inlet and an outlet;
a flushing reservoir situated between the inlet and the outlet and having
an overlying, resiliently deformable dome forming a portion of the
housing, the flushing reservoir providing means for flushing fluid through
the flow control device by application of percutaneous manual pressure to
the device to depress the dome;
a first valve situated between the inlet and the flushing reservoir, for
controlling fluid flow from the inlet to the outlet;
a second valve situated between the flushing reservoir and the outlet, for
controlling fluid flow from the inlet to the outlet;
first fluid conduit means for directing fluid through the first and second
valves as the fluid passes through the flow control device;
second fluid conduit means for directing fluid through the second valve and
bypassing the first valve as the fluid passes through the flow control
device; and
means for selectively directing fluid either through the first or second
fluid conduit means, the fluid directing means including a selectively
positionable plug movable between a first position wherein the second
fluid conduit is open to fluid flow therethrough and a second position
wherein the second fluid conduit is closed to fluid flow therethrough, and
a magnetically polarized, percutaneously manipulable cam rotatable between
a first position and a second position, the plug having means for
occluding the second fluid conduit at one end and a cam rider at another
end, wherein the cam rider interacts with the cam such that rotation of
the cam between its first and second positions simultaneously moves the
plug between its first and second positions.
20. A flow control device as set forth in claim 19, wherein the first and
second valve means each include a base having a fluid passageway
therethrough and a valve seat surrounding a portion of the fluid
passageway, and a flow control member which contacts the valve seat in a
manner normally occluding the fluid passageway but selectively opening to
permit controlled unidirectional flow therethrough.
21. A flow control device as set forth in claim 19, including a siphon
control device adjacent to the outlet, which prevents fluid flow through
the flow control device in the absence of positive upstream fluid pressure
through the device or in response to negative hydrostatic downstream
pressure on the device.
22. A flow control device as set forth in claim 19 including means for
occluding a portion of the flow control device adjacent to the inlet by
application of manual percutaneous pressure to the flow control device.
23. A fluid flow control device, comprising:
a housing having an inlet and an outlet;
a first fluid flow pathway through the housing from the inlet to the
outlet, the first fluid flow pathway having first means for resisting
fluid flow therethrough;
a second fluid flow pathway through the housing from the inlet to the
outlet, the second fluid flow pathway having second means for resisting
fluid flow therethrough; and
means for selectively directing fluids through one of the first or the
second fluid flow pathways, the fluid directing means being actuable by
percutaneous manipulation of the device when subcutaneously implanted;
wherein the means for selectively directing fluids through either the first
or the second fluid flow pathways includes means for occluding the second
fluid flow pathway, comprising a selectively positionable plug movable
between a first position wherein the second fluid flow pathway is open to
fluid flow therethrough, and a second position wherein the second fluid
flow pathway is closed to fluid flow therethrough.
24. A fluid flow control device as set forth in claim 23, wherein the means
for occluding the second fluid flow pathway includes a magnetically
polarized, percutaneously manipulable cam rotatable between a first
position and a second position, the plug having an occluder at one end and
a cam rider at another end, wherein the cam rider interacts with the cam
such that rotation of the cam between its first and second positions
simultaneously moves the plug between its first and second positions.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to surgically implanted physiological
shunt systems and related flow control devices. More particularly, the
present invention relates to shunt systems including one-way flow control
valves for controlling the flow of cerebrospinal fluid out of a brain
ventricle and preventing backflow of fluid into the brain ventricle.
In the medical arts, to relieve undesirable accumulation of fluids it is
frequently necessary to provide a means for draining a fluid from one part
of the human body to another in a controlled manner. This is required, for
example, in the treatment of hydrocephalus, a ailment usually afflicting
infants or children in which fluids accumulate within the skull and exert
extreme pressure and skull deforming forces.
In treating hydrocephalus, cerebrospinal fluid accumulated in the brain
ventricles is typically drained away utilizing a drainage or shunt system
including a catheter inserted into the ventricle through the skull, which
is connected to a tube that conducts the fluid away from the brain to be
reintroduced into the peritoneal cavity or into the vascular system, as by
extending a distal catheter through the patient's jugular vein to the
atrium portion of the heart. To control the flow of cerebrospinal fluid
and maintain the proper pressure in the brain ventricle, a pump or valve
is placed in the conduit between the brain and the peritoneal cavity or
the heart. An exemplary flow control device is found in U.S. Pat. No.
4,560,375.
Although such drainage systems have provided successful results, a problem
of over drainage of the cerebrospinal fluid from the brain ventricles
sometimes exists. Over drainage of cerebrospinal fluid may result in
excessive reduction of the cerebrospinal fluid pressure within the brain
ventricles and predispose the development of a subdural hematoma or
hydroma, and excessive reduction of ventricular size leading to shunt
obstruction because of impingement of the ventricular walls on the inlet
holes of the ventricular catheter. This over drainage can be caused by the
siphoning effect of hydrostatic pressure in the distal shunt catheter. The
siphoning effect of hydrostatic pressure may be created by the elevation
of the ventricular catheter inlet with respect to the distal catheter
outlet (i.e., when the patient sits, stands or is held erect). In order to
prevent such over drainage caused by the siphoning effect of hydrostatic
pressure in the distal shunt catheter, siphon control devices have been
placed in the conduit, typically between the flow control device and the
peritoneal cavity or the heart. An exemplary siphon control device is
found in U.S. Pat. No. 4,795,437.
It is desirable in some instances to permit the physician to be able to
alter the flow characteristics through the drainage system after it has
been subcutaneously implanted. To this end, on-off devices have been
provided for implantation as a portion of the fluid conduit, as an
additional element of the shunt. An exemplary on-off device is shown in
U.S. Pat. No. 3,827,439.
Prior physiological shunt systems have failed to provide, however, a flow
control device which permits only unidirectional flow through the shunt
system, prevents over drainage caused by the siphoning effect of
hydrostatic pressure in the distal shunt catheter, and permits the flow
characteristics through the shunt to be altered percutaneously after the
shunt system has been surgically implanted. Further, existing flow control
devices extensively used in connection with the treatment of hydrocephalus
typically provide only a single pre-set resistance to the flow of excess
cerebrospinal fluid through the shunt system, which cannot be varied
except to prevent fluid flow through the shunt by means of an on-off
valve.
Accordingly, there has been a continuing need in the medical arts for
convenient and effective physiological drainage devices for controlling
the flow of fluid from one part of the body to another, which are
relatively inexpensive to manufacture and can be constructed substantially
of non-metallic parts which are not subject to adhering to one another and
causing a malfunction of the device. A flow control device is needed which
permits fluid flow therethrough only when upstream fluid pressure exceeds
downstream fluid pressure by a selected pressure differential, and which
also provides means for altering the selected pressure differential by
percutaneous manipulation of the device when it is subcutaneously
implanted.
Additionally, a novel flow control device for use in a physiological shunt
system is needed which utilizes a plurality of flow control valves having
different flow control characteristics. Such a device should provide
alternative fluid pathways therethrough such that selection of the desired
fluid pathway can be made by the selective percutaneous manipulation of
the device when it is subcutaneously implanted. Moreover, such a flow
control device is needed which incorporates an integral siphon control
device that opens only in response to positive upstream fluid pressure,
and recloses or remains closed in the absence of such positive upstream
fluid pressure or in response to negative downstream hydrostatic pressure
on the device. As will become apparent from the following description, the
present invention satisfies these needs and provides other related
advantages.
SUMMARY OF THE INVENTION
The present invention resides in a physiological shunt system for
controlling the flow of fluid from one part of the body to another, which
is constructed substantially of non-metallic materials and provides
trouble-free and reliable operation in use. The shunt system of the
present invention is relatively inexpensive to manufacture, and can be
easily modified to provide a variety of pressure/flow characteristics. In
accordance with the present invention, a flow control device for use in a
subcutaneously implanted physiological shunt system includes a housing
having an inlet and an outlet, a fluid flow path through the housing from
the inlet to the outlet, and means for controlling fluid flow through the
fluid flow path. The controlling means includes means for permitting fluid
flow through the fluid flow path when upstream fluid pressure exceeds
downstream fluid pressure by a selected pressure differential, and means
for altering the selected pressure differential by percutaneous
manipulation of the flow control device when it is subcutaneously
implanted.
In a preferred form of the invention, the controlling means includes a
first normally closed valve which opens to permit fluid flow through the
fluid flow path when upstream fluid pressure exceeds downstream fluid
pressure by a first pressure differential, and a second normally closed
valve which opens to permit fluid flow through the fluid flow path when
upstream fluid pressure exceeds downstream fluid pressure by a second
pressure differential. Preferably, the first pressure differential is
greater than the second pressure differential.
The fluid flow path includes a first fluid conduit for directing fluid
through the first and second normally closed valves, and a second fluid
conduit which bypasses the first normally closed valve and directs fluid
through the second normally closed valve only. The means for altering the
selected pressure differential comprises means for selectively directing
fluid either through the first or second fluid conduits.
The first and second normally closed valves each include a base having a
valve passageway therethrough, and a valve seat surrounding a portion of
the valve passageway. A flow control member contacts the valve seat in a
manner normally occluding the valve passageway, but selectively opens to
permit controlled unidirectional flow therethrough. Each flow control
member includes a central support and a resilient membrane. The central
support is attached to the base and extends therefrom to support the
resilient membrane. The resilient membrane is generally arch-shaped and
has a portion thereof capable of engaging the valve seat to occlude the
valve passageway.
A variety of pressure/flow characteristics can be provided by the flow
control device of the present invention by manufacturing the normally
closed valves with different resilient membranes of varying thicknesses.
The resistance to flow past a normally closed valve increases with an
increase in membrane thickness.
The means for selectively directing fluid either through the first or
second fluid conduits includes means for occluding the second fluid
conduit means. This occluding means includes a selectably positionable
plug movable between a first position wherein the second fluid conduit is
open to fluid flow therethrough, and a second position wherein the second
fluid conduit is closed to fluid flow therethrough. The occluding means
further includes a magnetically polarized, percutaneously manipulable cam
which is rotatable between a first position and a second position. The
plug has an occluder at one end and a cam rider at another end. The cam
rider interacts with the cam such that rotation of the cam between its
first and second positions simultaneously moves the plug between its first
and second positions to, selectively, open and close a portion of the
second fluid conduit to fluid flow therethrough.
In order to provide the desired resistance to adhesion between various
components of the flow control device, particularly during storage, rigid
components of the valve are generally formed of a rigid polypropylene
material, while elastic components, such as the valve resilient membranes,
are preferably molded of a silicone elastomer material.
An intermediate fluid passageway between the first and second normally
closed valves is configured to provide a flushing reservoir, and integral
flow occluders are provided generally adjacent to the inlet and the
outlet, all of which are operated by percutaneous finger pressure applied
to the device. Through selective application of percutaneous pressure to
the flow occluders and the flushing reservoir, fluid within the reservoir
can be selectively flushed both proximally and distally through the
device.
A siphon control device is situated between the second normally closed
valve and the outlet, to prevent fluid flow through the flow control
device in the absence of positive upstream fluid pressure or in response
to negative downstream hydrostatic pressure. The siphon control device
comprises an integral housing including a pair of spaced, substantially
parallel, flexible diaphragms, and a base invested within the housing.
Other features and advantages of the present invention will become apparent
from the following more detailed description, taken in conjunction with
the accompanying drawings which illustrate, by way of example, the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate the invention. In such drawings:
FIG. 1 is a perspective view of a flow control device having selectable
alternative fluid pathways, embodying the invention;
FIG. 2 is an enlarged vertical section taken generally along the line 2--2
of FIG. 1;
FIG. 3 is a horizontal section taken generally along the line 3--3 of FIG.
2, illustrating the configuration of the flow control device when the
second fluid conduit is open to fluid flow;
FIG. 4 is a vertical sectional view similar to that illustrated in FIG. 2,
illustrating the manner in which fluid flows through the flow control
device, bypassing a first valve and then past a second valve when the
second fluid conduit is open to fluid flow therethrough; and
FIG. 5 is a vertical sectional view similar to that illustrated in FIGS. 2
and 4, illustrating the manner in which fluid flows through the flow
control device past both the first and second valves when the second fluid
conduit is occluded.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in the drawings for purposes of illustration, the present
invention is concerned with an improved flow control device, generally
designated in the accompanying drawings by reference number 10. The
improved flow control device 10 is intended for use in a surgically
implanted physiological shunt system for draining fluid from one portion
of the body to another. In order to connect, for example, the device 10 in
such a system, the device includes an inlet connector 12 and an outlet
connector 14 which each receive one end of a piece of surgical tubing (not
shown). The ends of the surgical tubing are placed over the connectors 12
and 14 and secured thereon by a single ligature just inside of an annular
ridge 16 formed near the end of each connector.
When the flow control device 10 is used in a drainage system intended for
the treatment of hydrocephalus, the inlet connector 12 is fluidly
connected with a proximal catheter which is inserted through the skull
into a brain ventricle containing cerebrospinal fluid under pressure. The
outlet connector 14 is fluidly connected to a distal catheter which serves
to discharge cerebrospinal fluid into, for example, the atrium portion of
a patient's heart. Ordinarily the flow control device 10 will be
surgically implanted on the patient's skull with a flap of skin overlying
the device. To facilitate holding the device in its desired position after
implantation, a generally flexible mounting plate 18 can be provided with
one or more suture holes.
As will become apparent from the following description, the present
invention provides a highly reliable flow control device having selectable
alternative fluid pathways which permit the flow control characteristics
of the device 10 to be altered when subcutaneously implanted by
percutaneous manipulation of the device. The present invention provides a
highly reliable flow control device designed to prevent valve seat
deformation and membrane to valve seat sticking, and to facilitate
implantation by eliminating components to be connected or adjusted other
than the surgical tubing to the device itself.
In accordance with the present invention, the flow control device 10
includes a pair of relatively rigid, molded, plastic bases 20 and 22
invested within a resiliently flexible housing 24 which, together, define
a fluid flow path through the housing from the inlet connector 12 to the
outlet connector 14. Two normally closed valves 26 and 28 are provided
within the fluid flow path to restrict the flow of fluid through the
device 10. The housing 24 and the second base 22 cooperate to provide a
siphon control device 30, situated between the second valve 28 and the
outlet connector 14, which prevents fluid flow through the device 10 in
the absence of positive upstream fluid pressure or in response to negative
downstream hydrostatic pressure on the device. Further, the housing 24 and
the first base 20 cooperate to define a pump or flushing reservoir 32
between the inlet connector 12 and the second valve 28.
Two alternative fluid conduits, defining portions of the fluid flow path
through the device 10, are provided in order to permit the flow control
characteristics of the device 10 to be altered by percutaneous
manipulation of the device when it is subcutaneously implanted. A first
fluid conduit 34 directs fluid through both the first and second normally
closed valves 26 and 28. A second fluid conduit 36 bypasses the first
normally closed valve 26 and directs fluid through the second normally
closed valve 28 only.
More specifically, and as shown best in FIGS. 2-5, the bases 20 and 22
interfit with one another and are integrally formed with, respectively,
the inlet and outlet connectors 12 and 14. The first or proximal base 20
defines an inlet flow channel 38 extending through the inlet connector 12
to a first valve housing 40 in which the first normally closed valve 26 is
positioned. The first base 20 also forms a bottom plate 42 for the
flushing reservoir 32, a second valve housing 44 for supporting the second
normally closed valve 28, and a snap-fit interlocking barbed connector 46.
Each of the valve housings 40 and 44 include a valve support plate 48
having a centrally positioned valve-supporting aperture 50, and three
surrounding apertures 52 which permit fluid flow through the supports 48.
Adjacent to each of the supports 48, the valve housings 40 and 44 define
generally cylindrical valve chambers 54 into which the valves 26 and 28
extend. After the first valve 26 is secured within the first valve housing
40, a first valve housing cap 56, having two apertures 58 therethrough, is
securely fixed to the base 20 opposite the support 48 to enclose the first
valve 26 within its valve chamber 54. After the second valve 28 is secured
within the second valve housing 44, a second valve housing cap 60 is
securely fixed to the base 20 opposite to the support 48 to enclose the
second valve within its valve chamber 54. An intermediate flow channel 62
extends from the second valve chamber 54 through the connector 46 to
direct fluids from the first base 20 to the second base 22.
As shown best in FIG. 5, the fluid flow path extending from the inlet flow
channel 38 upwardly through the apertures 52, past the first valve 26, and
then through the apertures 58 of the housing cap 56 comprises a portion of
the first fluid conduit 34. A bypass conduit 64 extends beneath the
support 48 of the first valve housing 40 between the inlet flow channel 38
and the flushing reservoir 32.
The barbed connector 46 extends from the first base 20 generally opposite
to the inlet connector 12. A pair of splines (not shown) extend from the
first base 20 adjacent to the connector 46 and, together with the
connector 46, interact with corresponding portions of the second base 22
to prevent tensile and torsional movement of the proximal and distal bases
20 and 22 with respect to one another.
The second or distal base 22 is integrally formed with the outlet connector
14 which defines an outlet flow channel 66 therethrough. The second base
22 defines a portion of the siphon control device 30. A connector
receptacle 68 is provided in the proximal end of the second base 22 for
receiving the barbed connector 46 therein. Spline receiving slots (not
shown) are also provided in the proximal end of the second base, to
slidably receive and substantially envelope the splines as the connector
46 is inserted into the receptacle 68.
The flexible housing 24 is provided in two parts: a first or inlet housing
body 24a into which the first base 20 is invested, and an outlet or second
housing body 24b which is sealed by a suitable adhesive 70 to the inlet
housing body 24a in order to provide a continuous elastomeric exterior to
the device 10, with the exception of the inlet and outlet connectors 12
and 14 which extend therefrom. The inlet housing body 24a is integrally
formed with the mounting pad 18 and includes an inlet aperture through
which the inlet connector 12 extends, an inlet occluder wing 72 which
generally overlies the first valve housing cap 56, a resiliently flexible
dome 74 for the flushing reservoir 32, and a distal occluder wing 76
generally overlying the support 48 of the second valve housing 44.
In order to provide a fluid-tight seal between the inlet connector 12 and
the housing 24a, a tube 78 is placed over a portion of the inlet connector
and secured in place by means of an over-suture 80. A silicone adhesive 82
is then injected into the remaining gap between the housing 24a and the
inlet connector 12. This same sealing arrangement is utilized between the
housing 24b and the outlet connector 14.
The inlet occluder wing 72 is positioned over the apertures 58 of the first
valve housing cap 56 to facilitate occluding a portion of the first fluid
conduit 34 by pressing the wing 72 downwardly. Depressing the wing 72 and
occluding the apertures 58, when the bypass conduit 64 is also occluded,
prevents proximal fluid flow from the flushing reservoir 32, defined by
the dome 74 and the bottom plate 42, when the dome is pressed downwardly
by manual percutaneous pressure. The dome 74 is preferably molded of a
silicone elastomer material and is designed to permit injection into the
flow control device 10 by a hypodermic needle through the dome. The bases
20 and 22 are preferably molded of a polypropylene material which provides
sufficient rigidity to prevent a needle from inadvertently passing through
the device 10 if an injection is made into the flushing reservoir 32. The
construction of the bases 20 and 22 and the housing 24 helps to guide a
physician in manually percutaneously manipulating the device 10 when
subcutaneously implanted, for purposes of flushing the shunt system.
The distal occluder wing 76 is positioned over the support 48 of the second
valve housing 44 to facilitate occluding the apertures 52 therethrough.
This is accomplished by pressing the wing 76 downwardly, which effectively
prevents distal fluid flow from the flushing reservoir 32 when the dome is
pressed downwardly by manual percutaneous pressure.
The outlet housing body 24b surrounds a portion of the second base 22 to
define the siphon control device 30 which is similar to that shown and
described in U.S. Pat. No. 4,795,437, the contents of which are
incorporated herein by reference. The siphon control device 30 includes an
outer wall 84 and an inner wall 86 which is situated within and encircled
about by the outer wall. The intermediate flow channel 62 directs fluid
from the valve chamber 54 of the second valve housing 44 to a central SCD
reservoir 88 defined as the area between the inner wall 86 and the outer
wall 84. The outlet flow channel 66 extends through the inner wall 86 to
the distal end of the outlet connector 14.
As can be best seen in FIG. 3, the outer wall 84 is generally circular in
shape, and is spaced from and encircles the inner wall 86. The inner wall
is also generally circular in shape, and defines an SCD outlet chamber 90
which is adjacent to and in fluid communication with the outlet flow
channel 66. The inner wall 86 is constructed to have substantially
parallel upper and lower seating surfaces 92, and it effectively forms a
barrier separating the SCD reservoir 88 from the SCD outlet chamber 90.
The outlet housing body 24b is provided with a pair of spaced,
substantially parallel, flexible elastic diaphragms 94 which are fixed
about their peripheries adjacent to the outer wall 84. Each diaphragm has
an inner surface which defines the upper and lower limits of the SCD
reservoir 88 and the SCD outlet chamber 90, and an outer surface which
forms an exterior surface of the siphon control device 30. The diaphragms
94 are situated on opposite sides of the inner wall 86 to position a
portion of each inner surface thereof in contact with an adjacent one of
the seating surfaces 92 and form a seal therebetween which prevents fluid
flow between the intermediate flow channel 62 and the outlet flow channel
66.
The second housing body 24b further includes integral offset rings 96 which
surround each diaphragm 94 to inhibit overlying tissue from occluding the
siphon control device 30 when implanted into a patient. An aperture is
provided through the housing 24b through which the outlet connector 14
extends. A fluid tight seal is effected between the housing outlet
aperture and the outlet connector 14 utilizing a tube 78, an over-suture
80 and an adhesive 82, as described above in connection with the inlet
housing body 24a and the inlet connector 12.
In use, the diaphragms 94 normally lie against and interact with the
seating surfaces 92 of the inner wall 86 to close the device 10 to fluid
flow. The diaphragms 94 move away from the seating surfaces 92, however,
in response to a minimal level of positive fluid pressure within the SCD
reservoir 88 to permit passage of fluid from the intermediate flow channel
62 to the outlet flow channel 66. The diaphragms 94 close and seal upon
the seating surfaces 92 once again in the absence of such positive
upstream fluid pressure, or in response to negative downstream hydrostatic
pressure in the SCD outlet chamber 90. The siphon control device 30 thus
minimizes the undesirable consequences attendant to excessive overdrainage
of fluid due to the siphoning effect of hydrostatic pressure.
Each of the normally closed valves 26 and 28 extend from their respective
supports 48 into the valve chambers 54 of the first and second valve
housings 40 and 44, respectively, for controlling the flow of
cerebrospinal fluid out of a brain ventricle. Each normally closed valve
26 and 28 comprises a flow control member, including a central support 98
and a resilient membrane 100 molded of a synthetic polymer material
different from the material of the first base 20. The resilient membrane
100 is normally biased to close communication between the inlet flow
channel 38 and the intermediate flow channel 62, but will open to permit
flow through the adjacent apertures 52 when the pressure on the inlet or
proximal side of the resilient membrane exceeds the pressure on the outlet
or distal side by a predetermined amount. Moreover, should the pressure on
the distal side of the resilient membrane 100 ever exceed the pressure on
the proximal side, tending to cause flow in a reverse direction through
the normally closed valves 26 and 28, the membrane 100 will seal tightly
against a valve seat 102 provided on the adjacent support 48, to prevent
any such reverse fluid flow.
The first or proximal base 20 is preferably formed of a polypropylene
material, and the membrane 100 is preferably formed of a silicone
elastomer material. Both polypropylene and elastomer materials have been
shown to produce an acceptable level of tissue reaction, and the use of
this particular duality of materials, in contrast to the use of only a
single material, markedly decreases the chances of the membrane 100
adhering to any portion of the valve seat 102 which would clog the fluid
pathway through the device 10 and defeat the purpose of the device.
The membrane 100 has an arch-shape, as for example a second of a sphere,
and is designed to contact the valve seat 102 generally along the outer
edges of the membrane in a manner surrounding the apertures 52. The
membrane 100 is secured in place adjacent to the valve seat 102 by the
central support 98 which is fixed within the valve-supporting aperture 50
through each support 48.
Since the valves 26 and 28 are primarily designed to provide controlled
resistance to cerebrospinal fluid flow from a brain ventricle to another
location in the body, it will be appreciated that a doctor must be able to
select valves having the particular pressure/flow characteristics desired
for each individual application. That is, a valve which permits flow at a
relatively low pressure differential may not be suitable where the
maintenance of a higher pressure differential is indicated. Toward this
end, in order to provide a flow control device with a variety of different
pressure/flow characteristics, the first normally closed valve 26 has a
different pressure/flow characteristic than the second normally closed
valve 28. More particularly, the first normally closed valve 26 is
provided with a relatively thick membrane 100, whereas the second normally
closed valve 28 is provided a relatively thin membrane 100. Resistance to
flow increases with an increase in membrane thickness. Thus, the first
normally closed valve 26 provides a higher degree of resistance to flow
through the device 10 than the second normally closed valve 28.
Recognizing that fluid will tend to take the path of least resistance, it
can be seen that fluid permitted to flow through the second fluid conduit
36, thereby bypassing the first normally closed valve 26, will experience
a lesser degree of resistance to flow than if caused to flow through the
first fluid conduit 34. FIGS. 1 through 4 illustrate the configuration of
the flow control device 10 wherein the second fluid conduit 36 is open to
fluid flow therethrough. If the bypass conduit 64 within the first base 20
below the first valve housing 40 is unoccluded, fluid is permitted to flow
from the inlet flow channel 38 directly into the flushing reservoir 32 for
introduction on the inlet or proximal side of the second normally closed
valve 28. Since both of the normally closed valves 26 and 28 prevent
retrograde fluid flow, the fluid passes only through the second normally
closed valve 28 into the intermediate flow channel 62. Accordingly,
resistance to flow through the flow control device 10 when the second
fluid conduit 36 is open, is determined primarily by the second normally
closed valve 28. From the intermediate flow channel 62, the fluid then
passes through the siphon control device 30 to the outlet flow channel 66,
for delivery to a distal catheter.
In order to close the second fluid conduit 36 and thereby cause fluid
passing through the device 10 to pass through both the first and second
valves 26 and 28, means are provided for occluding the bypass conduit 64.
More specifically, a selectively positionable plug 104 is pivotally
mounted to a plug support 106 which extends upwardly from the bottom plate
42. The plug 104 includes an occluder 108 at one end and a cam rider 110
at another end. The occluder 108 is configured to permit fluid flow
through the bypass conduit 64, and particularly an outlet aperture 112,
when the plug 104 is pivoted into a first position (FIGS. 2-4).
Alternatively, the plug 104 may be pivoted into a second position (FIG.
5), wherein the occluder 108 overlies and occludes the outlet aperture
112, thereby closing the bypass conduit 64 to fluid flow therethrough.
In order to selectively position the plug 104 within the flushing reservoir
32, a magnetically polarized, percutaneously manipulable cam 114 is also
situated within the flushing reservoir 32. The cam 114 includes a
permanent magnet 116 having well defined north and south poles. The
permanent magnet 116 is mounted to the underside of a disc 118 which, in
turn, is rotatably mounted upon a cam support shaft 120 that extends
upwardly from the bottom plate 42. The disc 118 is provided with an
arcuate slot 122 extending through approximately a 180.degree. angle. A
first end 124 of the slot 122 is situated adjacent to the outer periphery
of the disc 118, while a second end 126 of the slot is situated much
closer to the center of the disc.
The cam rider 110 of the plug 104 is situated within the slot 122. As
illustrated in FIG. 2-4, when the cam rider 110 is positioned within the
first end 124 of the slot 122, the plug 104 is pivoted about the plug
support 106 to space the occluder 108 from the outlet aperture 112 of the
bypass conduit 64. As the cam 114 is rotated clockwise when viewed from
the perspective of FIG. 3, the cam rider 110 is drawn toward the center of
the disc 118 which causes the plug 104 to pivot in a manner causing the
occluder 108 to move toward the aperture 112. When, finally, the cam rider
110 is positioned within the second end 126 of the slot 122, the occluder
108 of the plug 104 is positioned directly against the portion of the base
20 surrounding the outlet aperture 112 in a manner preventing fluid flow
through the bypass conduit 64 and thereby occluding the second fluid
conduit 36.
With the second fluid conduit 36 so occluded by the plug 104, fluid
entering the inlet flow channel 38 must pass through both the first and
second normally closed valves 26 and 28 before exiting the device 10
through the outlet flow channel 66. Further, since the first normally
closed valve 26 provides a greater degree of resistance to flow than the
second normally closed valve 28, the first valve 26 primarily determines
the resistance to flow of the device 10 in this configuration.
Subsequently, when it is desired to permit fluid flow through the outlet
aperture 112 of the bypass conduit 64, the disc 118 is simply rotated in a
counterclockwise direction to pivot the plug 104 away from the outlet
aperture. Counterclockwise rotation of the disc 118 moves the cam rider
112 toward the periphery of the disc 118 as it follows the slot 122, until
the cam rider is once again positioned in the first end 124 of the slot.
The permanent magnet 116 secured to the underside of the disc 118 permits
the cam 114 to be rotated, as described above, by percutaneous
manipulation thereof when the device 10 is subcutaneously implanted. In
particular, a medical professional may turn the cam 114 by placing a
magnetically polarized ring 128 (schematically illustrated in FIG. 2)
directly over the flushing reservoir 32 of the device 10. With the
knowledge that clockwise rotation of the cam 114 will cause occlusion of
the second fluid conduit 36, and counterclockwise rotation of the cam will
cause the second fluid conduit to be open to fluid flow, the polarized
ring 128 is simply placed next to the skin and rotated in the direction
intended to cause the desired flow path configuration. It does not matter
how the polarized ring 128 is initially oriented over the flushing
reservoir 32 of the device 10, because as the ring 128 is rotated in the
desired direction, the magnetic poles of the ring will seek the opposite
poles of the permanent magnet 116. When the polarized ring 128 is aligned
with the permanent magnet 116 as shown in FIG. 2, further rotation of the
ring will tend to cause like rotation of the cam 114 until the cam rider
110 is positioned in either the first or second ends 124 and 126 of the
slot 122.
The design of the flow control device 10, permits percutaneous distal and
proximal flushing of fluid within the fluid reservoir 32 by percutaneous
manipulation when the device is subcutaneously implanted. In order to
flush the device 10 distally, the cam 114 is first rotated clockwise in
order to occlude the second fluid conduit 36. The inlet occluder wing 72
is pressed downwardly to occlude the apertures 58 through the first valve
housing cap 56. The dome 74 is then simply pressed downwardly to flush the
contents of the flushing reservoir 32 through the second valve housing 44,
past the siphon control device 30 and through the outlet flow channel 66.
Similarly, proximal flushing can be accomplished by first turning the cam
114 counterclockwise to open the bypass conduit 64 to fluid flow
therethrough, and by pressing downwardly on the distal occluder wing 76,
to occlude the apertures 52 of the second valve housing 44. The dome 74 is
then pressed downwardly to flush fluid proximally from the flushing
reservoir 32 out of the device 10 through the bypass conduit 64 and the
inlet flow channel 38.
From the foregoing it is to be appreciated that the present invention
provides a flow control device 10 for use in a subcutaneously implanted
physiological shunt system having selectable alternative means for
controlling fluid flow through the fluid flow path. Through the provision
of a first fluid conduit 34 which directs fluid through both the first and
second normally closed valves 26 and 28, and an alternative second fluid
conduit 36 which bypasses the first normally closed valve 26, means are
provided for permitting fluid flow when upstream fluid pressure exceeds
downstream fluid pressure by two different selected pressure
differentials. The construction of the flow control device 10 of the
present invention permits selective distal and proximal flushing of the
device through the application of manual percutaneous pressure, and
further permits the selected pressure differential to be altered, also
through percutaneous manipulation of the device when subcutaneously
implanted. The present invention provides a device by which the flow of
cerebrospinal fluid out of a brain ventricle can be controlled while
preventing the backflow of fluid into the brain ventricle, and inhibits
excessive drainage through the physiological shunt in the presence of
excessive downstream suction. Radiopaque indicators 130 may also be
provided to provide X-ray detectable indicators of valve type and flow
direction.
Although a particular embodiment of the invention has been described in
detail for purposes of illustration, various modifications may be made
without departing from the spirit and scope of the invention. Accordingly,
the invention is not to be limited, except as by the appended claims.
Top